3.  All sound is produced by  material sends through a thru  Frequency of = frequency of  Pitch =  High pitch = high  Low = low vibration frequency  Range  Below 20 Hz =  Above 20,000 Hz =  Young person can hear

4.  Compression   Pulse of  Rarefaction  Closing door   Molecules away from

5.  All  Sound is in than in  Sound is  Sound cannot  No compression/expansion,  There can be without produced

6.  Do you hear thunder or see lightning first?  Speed of sound in dry air @ is  increases speed  Each increase, speed of sound increases by  Speed of sound @ (~20°C) =  Speed of sound in a depends on, but on !!!

7.  proportional to the of a  objective 

8.  a sensation   BUT, related to  almost varies as the  unit =  increase of each = sound intensity increases by a  10 dB = 10 x as  20 dB = 10 x as ; 100 x as

9. Source of soundLevel (dB) Jet engine @ 30m140 Threshold of pain120 Loud rock music115 Old subway train100 Average factory90 Busy street traffic70 Normal speech60 Library40 Close whisper20 Normal breathing10 Hearing threshold0 TABLE 26.1; P394